A VOA reporter in Goma says a steady stream of civilians began heading south toward the city beginning in the morning.

Each side is blaming the other for starting the fighting. There was no immediate word on casualties.

M23 captured Goma in November before withdrawing under intense international pressure. Subsequent peace talks between the government and rebels have largely stalled.

The first troops of a U.N. "intervention brigade" arrived in Goma this month for their mission to combat M23 and other rebel groups.

The U.N. Security Council authorized the mission in March, after years of attempts by the DRC government to stabilize North Kivu and nearby provinces. The area is home to many rebel groups who fight over the region's mineral wealth.

U.N. Secretary-General Ban Ki-moon is visiting the Great Lakes region this week, including a stop in Congo's capital Kinshasa on Wednesday.

Earlier this month, a report by the U.N. Joint Human Rights Office accused both the DRC army and M23 of committing serious human rights violations.

It said combatants on both sides looted homes and raped civilians, among other atrocities.